import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  late AnimationController _controller;

  @override
  void initState() {

    _controller = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 1),
    );
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Title'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          FadeTransition(
            opacity: _controller,
            child: const FlutterLogo(size: 80),
          ),
          const SizedBox(
            height: 40,
          ),
          Padding(
            padding: const EdgeInsets.fromLTRB(10, 0, 0, 0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [
                ElevatedButton(
                    onPressed: () {
                      _controller.forward(); //正序播放一次
                    },
                    child: const Text("Forward")),
                ElevatedButton(
                    onPressed: () {
                      _controller.reverse(); //倒序播放一次
                    },
                    child: const Text("Reverse")),
              ],
            ),
          )
        ],
      ),
    );
  }
}
